Technical Field
The present invention relates to a key switch, especially relates to a hybrid digital analog key switch to generate both a digital signal and an analog signal (DA) from a single key switch after being depressed.
Description of Related Art
FIG. 1 is a prior art
FIG. 1 is a prior art US2010/0148999 which disclosed separate keys for outputting a digital signal and an analog signal in a keyboard. The prior art discloses an analog key 202 and a digital key 203. In operation, depressing the analog key cap 51 202 shall cause an analog signal output 220, and depressing digital key cap 51 203 shall cause a digital or on/off output 222. The analog key provides a variable output, and the digital key provides a momentary-on output. A plastic base 212 supports the key structure. A flexible PCB (circuit board) 210 is provided on top of the base 212. The PCB 210 includes circuit traces or connections that provide for electrical signals to be generated and communicated when keys are depressed. Circuit connection 236 is used to provide digital output 222, and circuit connection pads 230 and 231 are used to provide the analog output 220. The next layer is a flexible insulator 208, such as a flexible PCB without circuit connections. The next layer is another flexible PCB 206 that includes circuit traces or connections that work in conjunction with the connections on PCB 210 to provide for electrical signals to be generated and communicated when keys are depressed.
A relatively thin flexible layer 204 is provided above PCB 206. A flexible dome 215 is provided for analog key cap 51 202, and flexible dome 213 is provided for digital key cap 51 203. For the digital key, an actuator 214 is provided underneath the dome 213 that causes circuit trace 234 to be engaged with circuit trace 236 when the digital key cap 51 is depressed. When circuit trace 234 touches the circuit trace 236, a digital output 222 is provided. For the analog key, a conductive and flexible half-dome 216 is provided that flexes when depressed. The capacitance associated between circuit pad 231 and circuit pad 230 varies when analog key cap 51 is depressed. Essentially pad 231 and pad 230 are the two plates of a capacitor. The variable capacitance between these two plates is measured from signal trace 232 by sending this trace to capacitance reading circuitry.
The dedicated key design is not a convenient control device for a game player. A more favorable control device capable of outputting both a digital signal and an analog signal device needs to be devised.